Telegraphy.



E. s. HEURTLEY,

TELEGRAPHY. APPLICATION [ILED JUNE 24, 1916 Patented Dec. 4, 1917.

3 SHEETS-SHEET I //V VE/VTOR, rlwribf [ff/ll m 'E. s. HEURTLEY. TELEGRAPHY.

APPLICATION FILED JUNE 2 4, 1916.

Patmted Dec. 4, 1917.

3 SHEETS-SHEET 2- //VVE/VTOR,

ERNEST S. HEUBTLEY, 0F OXFORD, ENGLAND.

TELEGRAPHY.

aaaaoea Specification of Letters Patent.

Patented Dec. at, 191?.

Application filed June 24, 1916. Serial No. 105,778.

To all whom it may concern:

Be it known that I, EnNns'r SYDNEY HEURTLEY, a subject of His Majesty the King of England, and resident of Oxford, in the county of Oxford, Kingdom of England, have invented certain new and useful Improvements in Telegraphy, of which the following is a specification.

This invention relates to improvements in telegraphy and it has for its objects to provide a new and improved method of transmitting more than one message or impulse at the same time, and in the same direction over one conductor and selecting out these messages or impulsesto separate instruments at the distant end.

The improvements are applicable to land line, underground and submarine cables of almost any electrical time constants.

According to the present invention messages or impulses are sent into the line from each transmitter which messages or impulses respectively have different wave formations differing in their wave fronts. The diiference in waveformation is selected out by the receiving instruments at the distant end and correction currents are arranged from these instruments so as to correct, counteract or neutralize the eflect of the incoming current for one instrument on the other instrument.

It will be appreciated that the present invention does not resemble other previously proposed methods of simultaneously transmitting two messages in the same direction over one conductor, such as one in which both continuous and alternating or wave form current impulses are sent into the cable so that for one messageeach code or signal element comprises a single direct current impulse and for the other message each code or signal element comprises a considerable number of alternating or intermittent impulses, as in the present invention the selection of the separate messages at the receivingend depends solely upon the difiference in the wave formations or fronts of the impulses. I

The method employed in this invention will be described .with reference to diplex telegrapliy or the sending of two messages or impulses at the same time in one direction,

though it must be understood that with obvious modifications the invention may be used for sending several messages or impulses in the same direction at one time.

The sending apparatus for each channel may be the same as used up to the present and may consist of recorder transmission, Wheatstone, Morse, Hughes, or any other system On each of the channels; but with variations of resistance, inductance, voltage, capacity or any suitable combination of these in series or as shunts with the transmitting apparatus for each channel respectively, so as to vary the wave fronts for each channel. In place of or in addition to the before referred to means for altering the wave formations, varying degrees of marking to earthing on the sending transmitter may be used or a distributor or its equivalent to in sert varying degrees of earthing of adjustable frequency may be added.

Referring particularly to this diplex or two channel system :channel A could for instance consist of normal sending conditions through say a capacity shunted or otherwise. Channel B might then'consist of the same sending voltage but the transmitter might send to line through a resistance and no capacity. This would result in the wave front being less steep than in the conditions of channel A. This relative difference would be the same at the commencement and termination of every impulse sent through the line by each transmitter respectively.

In order to select out these difi'erent wave fronts and arrange that the signalsv should not destroy each other at the receiving end, although ll may use ordinary definite contact making relays or their equivalents, I prefer to use apparatus which give in the local circuit currents of approximately the same formation as are passing through the receiver; but the magnitude of which current is readily adjustable. The instrument described in the specification of my United ment of the prime mover, however small,

there is a proportional E. 'M. F. generated in the local circuit (in which the registering instrument is connected) and this E. M. F. for a given movement can be varied at will within a comparatively large margin. Two of these instruments would be required for a two channel circuit and they may be placed in series or parallel with each other, and each or both would be supplied with inductance, capacity, or resistance, or any combination of these in series and/0r parallel, and be so adjusted that one instrument (for channel A) is particularly susceptible to the steep wave front while the other tends to respond more readily to the slower rising wave front. The instrument for channel B may in certain cases be placed in series with the inductance which shunts the instrument for channel A.

In order to reduce still further the influence of the steep wave front on the instrument for receivlng from channel B (the receiving instrument for the more slowly rising wave front), another winding or its equivalent on receiving instrument of channel B may be connected up in such a position in the circuitsthat any current passing through this winding due to the steep wave front tends to neutralize the efiect of current from that steep wave front which may be passing through the main coil of that instrument. The current passing through this secondary winding on the receiving instrument of channel B may be modified for this special purpose by being made to pass through suitable capacity, resistance, inductance or any combination of these.

The receiving instrument of channel A may be adjusted so as to have a higher natural rate of oscillation of its moving parts relatively to the receiving instrument of channel B, thus tending still further to select out the different wave fronts. The ob- 7 ject of'these adjustments is to insure that the receiving instrument for channel A will respond to the initial impulse of the steep wave front an appreciable time before andor to a greater extent than the receiving in- Y strument for channel B, but on the other hand the receiving instrument B will respond to the impulses with the more slowly rising wave front'before,'and or to a greater extent than the receiving instrument A.

In order to prevent the slower or steady currents due to the sending instrument of channel A actuating the receivinginstrument of channelB, a current is taken from the local circuit of. the receiving instrument of channel A (in which the recording apparatus is placed) and passed through suitable resistances, inductances, capacities, or

any combination of these in parallel or se rles so as to obtain a curve similar in shape to the current passing through the main coil of the receiving instrument of channel B due to sending instrument of channel A, and passed through the same or another winding or its equivalent on the receiving instrument of channel B; but in such a direction and of such a strength that it neutralizes the effect of the current passing through the receiving instrument B from the line due to the sending instrument A.

In a similar way a local or correction current is derived from the local circuit of the receiving instrument of channel B suitably shaped as above and sent through the same or another winding on the receiving instrument of channel A to counteract the effect of the slower waves or steady currents passing through the said receiving instrument of channel A from the line which is caused by the sending instrument of channel B.

This, or any of these corrections, in place of or in addition to, acting on the recording instrument through the primary instruments may be made to act on the recording instrument direct. Capacity, inductance, or

the like, may be used as desired on the recording instrument for improving the working.

I do not confine myself to any special form of receiving instrument but mention the particular one described in the specification of my aforesaid Letters Patent.

It is obvious that the system can be readily worked on duplexed circuits; the sending for channel A say being through its ordinary block condensers shunted or unshunted and for channel B through resistance and or capacity, both being balanced in the ordinary way. If inductance is used for sending it would be placed between the transmitter and the apex of the bridge or between the transmitter and earth, as, for instance, at 11, 12 and 13 in Figure 1, or in the channel B in Fig. 2.

The ordinary method of shaping the signals by the use of capacity inductance and resistance may be used as required and the instrument may actuate relays in the normal way or other instruments.

In order that the invention may be more clearly understood and more readily carried into effect it is hereinafter described with reference to the accompanying drawings in which Figs. 1, 2, 3, and i, are diagrams showing possible sending arrangements for two channels arranged for duplex working though it must be clearly understood that letter E for the two wave formations for channels A and B respectively.

Fig. 8 is a diagram of the receiving end of a cable inwhich a rotating distributer is Leagues employed in order to obtain the correct phrase and formation of the signals.

Fig, 9 is a diagrammatic representation of the receiving instrument of the type shown in the aforesaid Letters Patent.

Referring more particularly to Figs. 1 to 3 of the drawings the numeral 6 indicates the sending apparatus for channel A which may be any of the present known methods ofsending. The numeral 7 similarly indicates the sending apparatus for channel B. The sending apparatus 6 is arranged to send through sending condensers 8 and with only a small amount of resistance or other retardation in its local circuit. However, instead of being condensers the numeral 8 may indicate resistance arms or means may be employed for the purpose. The essential point is that the wave front of 2c the E. M. F. impressed on the cable 10 from the sending apparatus 6 shall be different from that impressed on the cable 10 from the sending apparatus 7. In the diagrams shown in Figs. 6 and 7 the letter is supposed to be made with one positive impulse and with double the battery power for the channel B though it may be made with the same battery power, the speed, 2'. e., the letters per minute being the same in both cases. In so these figures the wave front or front position of the wave for the channel A is indicated by the letter 0; and that of the channel B by the letter 6.

In Fig. 1 the apparatus 7 is shown sending through one or more inductances 11, 12, and

13, which may or may not be shunted by resistances 14, 15, and 16, and through resistance arms 17 and 18. In place of the inductances11, 12, and 13, capacities, or capacities to and resistances such for instance as the artificial line 19 as shown in Fig. 2, may be used and the arms 17, 18, may be capacities shunted or otherwise as shown in Figs. 3 and 2.

In place of retardation beingused in the form of resistance, capacity or the like, a transmitter 20 sending fiat topped waves may be used such as a sine wave transmitter. Further, in place of the two sending apparatus 6 and 7 being in parallel they may be in to. series as shown in Fig. 4 and with any of these arrangements the coupling of either channel may be made through a transformer as shown with channel A in Fig. 4.

The condenser 21 in Fig. 4 is to more or less'short-circuit the sending apparatus 7 of channel B with regard to channel A.

Any combination of any of these methods of sending may be used and in addition different sending voltages may be used in chanco nel A and channelB. Further instead of or in conjunction with any or all of these devices for varying the wave front a variation of wave form may be obtained by variation in the relative amount of marking to at earthing of the transmitters in channel A any other suitable and channel B, that is by varying the relative lengths of time the current is applied to the time the cable or line is earthed.

Fig. 5 shows an example of the receiving side though it must be understood that any other form of connection or methods of, or combinations of inductances, capacities or resistances which allow one instrument to respond more readily to one form of wave front than the other may be used. The present example is given solely to indicate the system. The instrument described in the aforesaid Letters Patent is used in this description although it must be understood that any other method of amplifying the to signals or in some cases even direct working relays may be used.

Referring to Fig. 5, which is purely diagrammatic, the invention is shown for simplicity of description applied for simplex as working although there is no reason why it should not be used for duplex working. As shown the numeral 10 represents the cable, 22, see-also Fig. 9, the magnifying instrument main receiving coil for channel A, and ee 23 a second winding on the same former. The numeral 24 indicates the fine heated wires which are mechanically connected to the instrument 22 so that by the movement of 22 being communicated to these wires at their position with reference to blasts of air issuing from slits in tubes 24: is altered and consequently their resistance is varied, upsetting the electrical balance of the local circuit 25 in which they are placed and cansing a current to circulate around the local receiving instrument 26, and through the resistance 27. The numeral 28 indicates the main receiving coil of the magnifying instrument for channel B, and 29 a second winding on the same former. Fine electrically heated wires 30 are mechanically connected to the coil 28 of the magnifying instrument and any movement of this instrument being communicated to these wires, their position with-reference to a blast of air is altered and consequently their resistance is varied which causes a current to circulate through the coil of the receiving instrument 31and the resistance 32. The references 33 and 34 indicate capacities and those 35, 36, 37, and 38 inductances.

Impulses arriving from the distant end with steep wave fronts will pass through the capacities 33 and 34 to a greater extent than will impulses with more slowly rising wave fronts which will pass in greater proportion through the inductances of the circuit.

Assuming that channel A has a compara- 12 tively steep wave front the commencement of this impulse will pass through 22 to a greater extent than it will pass through the instrument 28. This will cause a current to pass through the resistance 27 and the local receiving instrument 26 and a potential willbe generated in the inductances and resistances 39, 40, 41 and 42 whose values will be so adjusted that a current will pass through the second Winding 29 of the coil 28 of such a strength and such wave formation that it will neutralize the effect of that part of the current due 'to the transmitter of channel A (the steep wave front) which passes through the coil 28. Consequently for the steep wave front or the transmitter of channel A no signal will be recorded on the local instrument 31.

In the case of the slower wave front arliving from the transmitter of channel B,

provided the values of capacity and induction and resistance in the various circuits are correct, the current passing through the coil of instrument 28 will be stronger than that passing through 22 and a movement of 28 which will cause a current to circulate around the coil 31 and the resistance 32 will send a correcting current around the coil 23 which will prevent the coil 22 from being actuated by impulses from the cable of the wave front having a more gradual rise. The net result is that signals emanating from the transmitter of channel A with a steeper wave ment having the coil 22 and the local instrument 26 while signals emanating from the transmitter of channel B with the more gradual wave front influence only 28 and the local instrument 31.

Any other combination of capacities, inductances and resistances than thosegiven .above may be used, the \whole plan being to make one instrument more sensitive to the quick Waves than the other, which latter is more sensitive to the slow waves. of these methods of curbing may be used in the local circuits and resistance, capacity and inductances or any combination of them may be used in these local circuits to improve or facilitate the working.

In'some cases it is found difficult to obtain the correct formation with the before mentioned arrangement and in these cases I prefer to use a rotary distributer or its equivalent with two or more brushes, the segments of the distributer being connected to equal capacities or their equivalents. The distributer is kept revolving at a suitable speed and the impulses which preferably come from the local circuit of the amplifier are connected onto one brush and as the segments of the distributer pass under it the capacity attached to that segment becomes suitably charged. As the distributer revolves this charged segment passes under a second brush which is connected through suitable capacity, resistance, inductance or combination thereof to an instrument for receiving the impulses emanating from say the sending instrument for channel A, i. 6.,

front actuate only the instruof the revolving distributer the steep wave front. The adjustments are such that the capacity is not completely dis charged especially with regard to the slower Wave and the segment passes on to the second brush where the discharge takes place further through instrument B the adjustments of which circuit are such that instrument B is more sensitive say to the slower rising.

wave front.

The segments finally pass under a fourth brush which short circuits and consequently completely discharges the capacity connected to that segment. Suitable correcting impulses are obtained and made to act on the various circuits so that the signals from the various channels do not interfere with each other.

Referring to diagram Fig. 8 there is shown the arrangement for receiving the two wave fronts shown arranged for simplex Working for simplicity. In this diagram 10 is the line through which the impulses for channel A and B come; 43 is the main coil of the amplifying apparatus receiving impulses of both kinds from the cable having connected with it suitable capacity and induc'tance and resistance 44, 45, and 46 to obtain the correct shape of the impulses. 47 and 48 are the hot wires of this instrument. The central point of this instrument 49 is connected through a resistance 50 to a brush 1 which makes contacts with the segments 51, 52 to 59, etc. These segments are insulated and connected to capacities which in this case have their opposing plates joined together in one common plate 60.

This common plate is joined to the other side of the amplifying apparatus at 61, also through suitablecapacity 62 and a coil 63 to a receiving instrument which can be a plain recorder or preferably the main coil of another amplify'ng apparatus or other suitable receiving apparatus.

The other side of this coil 63 is joined to suitable adjustable resistance 64 and 65 and thence to brush 2. Y

The common capacity plate 60 is also joined through a suitable-capacity 66 and a coil of a second instrument 68 and thence to brush 3.

The circuit of the coil 63 may be adjusted so as to be more susceptible to the impulses with the steep wave front'while that of 68 brushes 2 and 3 successively so that anygiven impulse will first affect the instrument 63 and later the instrument 68.

The followlng is the action of the apparatus. An impulse is received from the line 10 and moves the coil 43. This causes an impulse to be thrown on to the local circuit between 49 and 61. This causes a difference of potential across the resistance 50 and charges a segment or segments, say segment 52 of the distributer through brush 1. This segment at some later interval comes under the brush 2 and discharges to a certainextent this coil 63 and resistance 64.

Across the resistance 50 is connected suitable electrical retardation which is represented in the drawing by the inductances 69 and 70 and the resistance 71 but which may be made up of capacity and resistance. This is joined on to the coil of another amplifying apparatus 76 the local circuit of which 74 and 75 is joined to resistance 65.

Now it is obvious that owing to the retardation-of the circuit 69, 70 and 71 that the impulses received through the channel A due to the steep wave front will be relatively smaller in the local circuit 74, 75, than the impulses received through the channel B due to the more slowly rising wave front, so that if the amplitude of the signals in the local circuit 74 and 75 from coil 76 be so adjusted that in the circuit from brush 2 through coil 63 these waves exactly neutralize the slow waves from the 'distributer capacity through brush 2, due to the slow waves from channel B, then the quicker impulses from channel A will remain passing through the coil 63 thoughreduced in amplitude. That is when'proper adjustment is obtained the algebraic sum of the currents passing through the coil 63 will be zero so far as the channel B is concerned but some positive quantity so far as channel A is concerned.

This actuates an amplifying apparatus, the local circuit of which 77, 78, works the receiving instrument 79 and also sends a current around a second winding on the same former of the coil 63 which current is suitably adjusted in direction and shape so as to give the correctly shaped signals and neutralize the overcurbing efiect of the sending apparatus and device 74, 75 for channel A.

It will thus be seen that the signals from the sending apparatus of channel A will be recorded on the receiving instrument 79, but that signals from the sending apparatus of channel B will not actuate the receiving instrument 79.

Signals from both the channel A and the channel B will be received at a later interval through circuit brush 3, 68, 66, and 61; but a current is received through the second windin on the former of'the coil 68, due to the di erence of potential across the resistance 64, and this'current is so formed and timed by the resistances and inductances or their equivalents 86, 87, and 88, and the position of the brush 3 relatively to the brush 2, that it exactly neutralizes the effect of the rival of the signals that the various receiving instruments are actuated,this time being adjusted by the speed of rotation of the distributer and the relative positions of the brushes which are adjustable.

Capacities 89 and 90 or their equivalent are placedin' the circuits of coils 68 and 63 respectively to overcome any slight disturbance which may take place as the brushes pass over the various segments of the distributer. In place of the distributer revolving the brushes may be made to revolve.

What I claim is:

1. In telegraphy, in which each impulse of current represents one or more elements of a Morse or other code, a line, means for producing and transmitting over the line more than one message in the same direction at the same time in the form of sets of impulses difiering in their wave fronts, and respective receiving means selectively responsive to the different sets of impulses by reason of the differences in the wave fronts.

2. In telegraphy, in which each impulse of current represents one or more elements of a Morse or other code, a line, means for transmitting over the line more than one message in the same direction at the same time in the form of sets of impulses and including electrical means for modifying the sets of impulses to difierentiate their wave fronts, and respective receiving means selectively responsive to the different sets of impulses by reason of the differences in the wave fronts.

3. In telegraphy, in which each impulse of current represents one or more elements of a Morse or other code, a line, means for producing and transmitting over the line more than one message in the same direction at the same time, and including means for applying different potentials for sending to line sets of impulses differing in their wave formations or front, and respective receiving means selectively responslveto the difi'erent sets of impulses by reason of the difierences in the wave fronts.

4. Intelegraphy, in which each impulse transmitting more than one message in the same direction at the same time over the line, with each message made up of sets of impulses having wave fronts characteristi- 5 cally individual thereto, and receiving apparatus including as many relay instruments as there are characteristically different sets of impulses and each relay instrument bein constructed to cause impulses in its loca circuit operating as correction currents to select out the signal in accordance with the wave fronts.

5. In telegraphy, in which each impulse of current represents one or more elements of a Morse or other code, a line, means for transmitting sets of impulses of current representing more than one message in the same direction at the same time over the linewith the impulse of each set having a wave front characteristically individual thereto, and receiving apparatus for the respective messages each constructed to be more sensitive to impulses of one wave front than to those of another wave front, whereby the messages are selectively received in accordance with the wave fronts characteristic thereto.

6. In telegraphy in which each .impulse of current represents one or more elements of a Morse or other code, a line, means for transmitting more than one message or impulse in the same direction at the same time over the line, said means including means for sending to line intelligible impulses differing in their wave formations or fronts, and receiving apparatus including receiving instruments and a distributer wlth current modifying means associated therewith for determining the times at which the various receiving instruments are brought into cir- 0 cuit.

7 In telegraphy, aline, means for transmitting more than one message or impulse transmitting more than one message or im-- pulse in the same direction at the same time over the line, and receiving apparatus including a distributer having a plurality of contacts so as to vary the time at which the various instruments are brought into circuit, capacities associated with the contacts for storing up energy received from one contact to deliver the same to another circuit, and a short-circuiting contact to fully discharge the segments of the distributer after they have delivered charges to the working circuits.

9. In telegraphy, in which each impulse of current represents one or more elements of a Morse or other code,.a line, means for transmitting more than one message or impulse in the same direction at the same time over the line, and receiving means selectively responsive to respective messages, each receiving means including a relay associated therewith and having means. for utilizing current from its local circuit for neutralizing the eflects on therelay of other received messages than the one for which the receiving means is selective.

In testimony whereof I have hereunto signed my name to this specification.

E. S. HEURTLEY. 

